feat(tours): import a ski track from GPX and keep it as recorded

SKI-02. Ski joins the types a GPX file can be imported as, offered in the
import preview's type field only: TREK routes no ski track, so the planner
never offers it. The preview asks for the discipline on purpose (alpine,
snowboard, cross-country or ski touring, none chosen at first) and, for
cross-country, the technique (classic, skating or unknown); Import waits
until both are named, and the technique stays in sight but dimmed for the
other disciplines. The track is stored exactly as recorded, with its file
name as provenance, its distance and heights from the file and no time:
no ski time is worked out and no hiking estimate stands in for one.

Opened in the planner, a ski track gets a rail card with its discipline on
a tinted tile, a cross-country technique as a badge beside it, the ski time
said as not worked out, and an info dot on what TREK does not say (snow,
avalanches, open runs, and that the 3D gradient colours are no difficulty
or avalanche rating). Change opens a dialog to classify the track again;
only the classification changes, through the offline core, with the
revision it was made at. Planning over the import is not offered for ski.
The existing 3D terrain view, the elevation profile and its focus work on
the track as for any import, with the standard map, topo and satellite and
no via ferratas. Lists, the day plan and the detail show the discipline as
a frosted corner badge on the tile and as a pill with the technique inside;
day assignment, copies and take-overs work as for any tour. The corner
badge is now one component that the winter label shares.

The server keeps tours.ski_discipline and tours.ski_technique (CHECK lists,
NULL on every other type), switches the ski type on without a routing
profile, refuses a ski import without its discipline, a technique outside
cross-country and ski fields on any other type, and takes a planned save's
classification off. PUT /api/trips/:tripId/tours/:placeId/ski classifies a
ski track again (place_edit, 409 on a stale revision, 400 for a tour that
is no ski track) and broadcasts tours:changed. GPX export names the
discipline (alpine_skiing, snowboarding, cross_country_skiing,
backcountry_skiing), and list_tours describes both fields with what a ski
track does not say. Ski is labelled plainly as Ski in every language, so
it no longer reads as ski touring.

wiki/MCP-Addon-Tools.md

@@ -237,7 +237,7 @@ The saved tours of a trip, as the Tours list and the tour detail show them, how
 
 | Tool | Description | Scope |
 |---|---|---|
-| `list_tours` | The saved tours of a trip: name, type (`hike`, `walk` for a city walk, `bike`, or `kayak` for a paddle tour), origin (`trek` for planned in TREK, `gpx` for a GPX import, `wanderer` for a wanderer snapshot), distance, ascent and descent (unknown for a paddle tour drawn in the planner), the stored routing limit of a hike on the SAC scale and its route choices (`hiking_preferences`), the winter label of a hike (`winter_activity`: `winter_hike` or `snowshoe`; a label only, the route and its time are planned as for any hike, never a statement about winter conditions), the boat, water and chosen speed of a paddle tour, the check bench of a paddle tour (`paddle_check`: how far the OpenStreetMap obstacle data covers its route and how many obstacles are open, to check again or decided; a planning status, never a safety or legal clearance), for a city walk how many stations it has (`station_count`), their stays as far as entered and how many have none, whether a tour still waits for its way to be planned (`route_pending`: saved with its points only, its distance and walking time unknown until someone opens it in the planner and saves it), the `revision` (raised by every saved change of the tour), and the days of the trip each tour is on | `trips:read` |
+| `list_tours` | The saved tours of a trip: name, type (`hike`, `walk` for a city walk, `run`, `bike`, `kayak` for a paddle tour, or `ski` for a ski track), origin (`trek` for planned in TREK, `gpx` for a GPX import, `wanderer` for a wanderer snapshot), distance, ascent and descent (unknown for a paddle tour drawn in the planner), the stored routing limit of a hike on the SAC scale and its route choices (`hiking_preferences`), the winter label of a hike (`winter_activity`: `winter_hike` or `snowshoe`; a label only, the route and its time are planned as for any hike, never a statement about winter conditions), the classification of a ski track (`ski_discipline`: `alpine`, `snowboard`, `cross_country` or `touring`; `ski_technique` for cross-country only: `classic`, `skating` or `unknown`; a ski track is imported from a GPX file and kept as recorded, never routed, has no ski time worked out and says nothing about snow, avalanches or open runs), the boat, water and chosen speed of a paddle tour, the check bench of a paddle tour (`paddle_check`: how far the OpenStreetMap obstacle data covers its route and how many obstacles are open, to check again or decided; a planning status, never a safety or legal clearance), for a city walk how many stations it has (`station_count`), their stays as far as entered and how many have none, whether a tour still waits for its way to be planned (`route_pending`: saved with its points only, its distance and walking time unknown until someone opens it in the planner and saves it), the `revision` (raised by every saved change of the tour), and the days of the trip each tour is on | `trips:read` |
 | `get_tour_plan` | One tour: its facts, its ordered control points, its provenance (where it came from, when, and whether it was changed in TREK since) and its days. A control point can carry a fixed leg to the next one: a via ferrata (`ferrata`) or a stretch drawn by hand (`free`), which no router planned or checked. A shaping point (`shaping: true`) only steers the route and is no stop. A paddle tour also carries its obstacle checklist (`obstacle_check`): the obstacles of the OpenStreetMap data along its route, what the travellers decided about each, and their own portages and locks. The stations of a city walk carry every field spelled out: `key` (the same across saves), `name`, `stay_minutes` (`0` for a point only passed, `null` when not known), `importance` (`optional`, `must`, or `null` for normal), `protected` (a station a proposed change has to keep where it is; the travellers can still edit it) and `opening_hours` (as OpenStreetMap writes them, `null` when none is known). The full track geometry is not included | `trips:read` |
 | `find_tours_for_day` | The tours put on one day of a trip, with the same facts as `list_tours` | `trips:read` |
 | `get_city_walk_progress` | How far a city walk got on one day it is on: every station in order with its key, its status that day (planned, visited or skipped, as checked off in the day plan), importance, protection, stay and opening hours, what is still open, and the walking time of the whole walk. Visits belong to that day only. Reading changes nothing | `trips:read` |